Where lands are to be cleared of trees, the trees are firstly felled and then the stumps have to be treated in order to render them harmless to machinery subsequently used to treat the soil, such as ploughs, harrows and the like.
One device which has been employed for this purpose physically pulls the tree stump out of the ground by brute force. Apart from being extremely costly, such equipment has a tendency to create great cavities and unevenness in the land which requires that it must be treated to level it somewhat before a conventional tractor driven plough or the like can be passed over the land. Also, the stumps must still be removed or alternatively destroyed.
Accordingly a device has been available and is operating at the present time, wherein a substantially vertically orientated cutting or grinding disc or drum is mounted on a swivel arrangement on a tractor such that it can be swung to and fro over a stump to comminute it down to a suitable depth, for example 25 cm to 30 cm below the ground surface. The depth is chosen such that the stump is rendered harmless to tractors and other soil working implements which may be passed over the land.
In one currently available simple stump treating machine of this nature described in U.S. Pat. No. 3,732,905 (to Pickel) the cutting disc is mechanically driven directly from the conventional power take off of the tractor by means of Vee-belts. This means that articulation of the frame supporting the cutting or grinding disc is difficult, and restraints are placed on the position where flexible joints can be located.
In such an arrangement the cutting or grinding discs generally consumes at least a substantial proportion of the power output of the tractor's engine and, accordingly, the tractor cannot be driven whilst the cutting or grinding disc is in operation. This means that the disc must be allowed to slow down sufficiently after a stump has been treated at the substantial speed at which it rotates in operation, in order that the power take-off can be disengaged, and the tractor moved to another position in order to treat another stump. Clearly the slowing down and speeding up of the cutting or grinding disc takes an appreciable amount of time thereby consuming fuel and useful working life of the tractor and cutting or grinding disc assembly.
U.S. Pat. No. 3,198,224 to Hiley proposes an arrangement which avoids the disadvantage by employing an hydraulic motor which drives the cutting or grinding disc through a Vee-belt or drive chain. The whole drive and disc arrangement is carried at one end of a foldable boom connected to a tractor or other suitable vehicle. Such an arrangement is costly and unsuitable for application to a general purpose tractor or the like.
A further disadvantage of presently used cutting or grinding disc arrangements is that the discs themselves have cutting tip carriers to which the tips are usually affixed by brazing, attached thereto by means of bolts wherein the carriers have plain holes therein through which the bolts pass. Thus, if, as is not uncommon, a bolt shears off, the entire cutting disc is rendered inoperative whilst the stub of the bolt is removed. Such removal is also often not a simple matter.
It is the object of this invention to provide rotary tractor mounted cutting equipment in which the disadvantages described above, as applied to tree stump cutting or grinding assemblies, are decreased, at least to some extent.